Class 12 NEET Biology Principles of Inheritance and Variation Questions Part 1

Albinism is caused by the absence of the enzyme tyrosinase which is essential for the synthesis of the pigment from dihydroxy-phenyl-alanine. The gene for albinism (a) does not produce the enzyme tyrosinase but its normal allele (A) does. Thus, only homozygous individual (aa) is affected by this disease. Albinos (individuals with albinism) lack dark pigment melanin in the skin, hair and iris. Although albinos have poor vision yet they lead normal life. On the basis of principles of simple recessive inheritance, the probability of albinic child from a normally pigmented parents, will be 1∕4 or 25%.